Hybrid White Organic Light-emitting Diodes Research Articles

Hybrid White OLEDs with High Electroluminescence Efficiency and High Color Rendering Index Achieved by a Sandwich Interlayer Sensitizing Configuration

AbstractWhite organic light‐emitting devices (WOLEDs) exhibit promising applications as white illumination and background light, but achieving high efficiencies, and high color quality for the WOLEDs still remains difficult. Herein, to enhance exciton utilization and improve the color quality of WOLEDs, a new sandwich configuration of an ultrathin orange phosphorescent layer located between two blue thermally activated delayed fluorescence (TADF) layers is proposed, and the working mechanism is investigated. In this configuration, the interlayer sensitization from blue TADF layers to orange phosphorescent layer via efficient Förster energy transfer occurs, which effectively alleviates exciton quenching in emitting layers and thus results in excellent electroluminescence (EL) efficiencies and improved color quality. The obtained two‐color hybrid WOLED exhibits an external quantum efficiency (ηext) exceeding 27%, with Commission Internationale del'Eclairage (CIEx,y) coordinates of (0.335, 0.396) and a color rendering index (CRI) of 63. By further incorporating an ultrathin red phosphorescent layer between the orange phosphorescent layer and the blue TADF layer, the ηext maintains at 21.96% and the CRI increases to 91 (CIEx,y = 0.380, 0.366). These results demonstrate the proposed sandwich interlayer sensitizing configuration is an effective and feasible strategy for realizing high EL efficiencies and high color quality simultaneously for hybrid WOLEDs.

Highly efficient fluorescent and hybrid white organic light-emitting diodes based on a bimolecular excited system: publisher's note.

This publisher's note contains a correction to Opt. Lett.48, 5771 (2023)10.1364/OL.506371.

Constructing multifunctional deep-blue emitters with weak charge transfer excited state for high-performance non-doped blue OLEDs and single-emissive-layer hybrid white OLEDs

Deep-blue emitter with high photoluminescence efficiency (PLQY) is highly desirable in ultra-high definition displays and white solid-state lightings. In this work, two deep-blue phenanthro[9,10]imidazole derivatives, PPIS and PPPIS, with hot exciton property are successfully developed. Compared to PPIS, the embedded phenyl bridge in PPPIS is able to effectively increase the overlap of frontier molecular orbitals. In consequence, PPPIS shows higher oscillator strength and significantly enhanced PLQY. PPPIS also achieves better electroluminescence performance in non-doped device, showing deep-blue emission with Commission International de l'Eclairage (CIE) coordinates of (0.153, 0.087) and the maximum external quantum efficiency (EQEmax) of 8.5% with minuscule efficiency roll-off. Meanwhile, when PPPIS serves as the host for phosphor PO-01, high-efficiency orange phosphorescent device is obtained with high EQEmax of 29.8% and negligible efficiency roll-off at 1000 cd/m2. Further, efficient single-emissive-layer white device is assembled via utilizing PPPIS as a blue emitter as well as the host for PO-01 simultaneously, providing warm-white emission with CIE coordinates of (0.429, 0.433) at 1000 cd/m2, the forward-viewing EQEmax of 27.2% and maximum power efficiency (PEmax) of 80.1 lm/W, respectively. Our studies can establish a viable design strategy for deep-blue emitters in high-performance non-doped blue OLEDs and hybrid WOLEDs.

High-efficiency and low-efficiency roll-off fluorescence/phosphorescence hybrid white organic light-emitting diodes based on AIEgens with hot exciton property by strategically managing triplet excitons

OLEDs with efficient blue emission are fabricated using AIE materials. Utilizing TPB-AC enables high-efficiency two-color white OLEDs, and introducing a TTF layer significantly enhances the efficiency, the maximum efficiency increased to 23.2%.

Highly efficient fluorescent and hybrid white organic light-emitting diodes based on a bimolecular excited system.

A bimolecular excited system is considered as a promising candidate for developing white organic light-emitting diodes (WOLEDs) with reduced phosphorescent components. However, for actualizing high-performance WOLED, little attention has been paid to electromers compared to exciplexes. Herein, we construct the bimolecular excited system to prepare fluorescent WOLEDs by combining the electromer emission with the exciplex emission, achieving a maximum power efficiency of 11.8 lm/W with a color rendering index (CRI) of over 80. Furthermore, phosphorescent dopants are doped into an exciplex host to construct hybrid WOLEDs. The fabricated complementary-color and three-color devices achieve maximum efficiencies of 55.3 cd/A (46.8 lm/W) and 34.1 cd/A (26.8 lm/W), respectively. The spectral coverages of WOLEDs are broadened by the bimolecular excited system, and CRIs are further improved at high luminance. Our strategy may bring light to the future development of highly efficient WOLEDs with economy and sustainability.

Simultaneously Realizing High Efficiency and High Color Rendering Index for Hybrid White Organic Light-Emitting Diodes by Ultra-Thin Design of Delayed Fluorescence Sensitized Phosphorescent Layers.

In consideration of energy economization and light quality, concurrently attaining high external quantum efficiency (ηext ) and high color rendering index (CRI) is of high significance for the commercialization of hybrid white organic light-emitting diodes (WOLEDs) but is challenging. Herein, a blue luminescent molecule (2PCz-XT) consisting of a xanthone acceptor and two 3,6-diphenylcarbazole donors is prepared, which exhibits strong delayed fluorescence, short delayed fluorescence lifetime, and excellent electroluminescence property, and can sensitize green, orange, and red phosphorescent emitters efficiently. By employing 2PCz-XT as sensitizer and phosphorescent emitters as dopants, efficient two-color and three-color WOLED architectures with ultra-thin phosphorescent emitting layers (EMLs) are proposed and constructed. By incorporating a thin interlayer to modulate exciton recombination zone and reduce exciton loss, high-performance three-color hybrid WOLEDs are finally achieved, providing a high ηext of 26.8% and a high CRI value 83 simultaneously. Further configuration optimization realizes a long device operational lifetime. These WOLEDs with ultra-thin phosphorescent EMLs are among the state-of-the-art hybrid WOLEDs in the literature, demonstrating the success and applicability of the proposed device design for developing robust hybrid WOLEDs with superb efficiency and color quality.

High-performance single-emitting-layer hybrid white organic light-emitting diodes featuring a stable blue emission component from green thermally activated delayed fluorescence

In this work, we demonstrate single-emitting-layer hybrid white organic light-emitting diodes (WOLEDs) with high-efficiency and low efficiency roll-off. Here, the white emission arises from stable blue emission via electroluminescence (EL) spectral shift from green thermally activated delayed fluorescence (TADF) emitter and yellow phosphorescent emitter. WOLEDs shows a maximum current efficiency of 56.77 cd/A, maximum power efficiency of 50.19 lm/W, and maximum external quantum efficiency of 20.00%. Compared to the devices composed of conventional blue TADF emitters, the device based on EL spectral shift-induced blue emission exhibit higher performances, indicating that efficient white emission can be obtained without a typical blue emitter. Our study provides an alternative way to fabricate high-performance WOLEDs based on EL spectral shift technology.

Efficient, Color-Stable, and Long-Lived White Organic Light-Emitting Diodes Utilizing Phosphorescent Molecular Aggregates.

Highly efficient and stable single-stack hybrid white organic light-emitting diode (WOLED) devices are developed using two emissive layers: one with amber-colored phosphorescent molecular-aggregate emission from the Pd(II) complex, Pd(II) 7-(3-(pyridine-2-yl-κN)phenoxy-κC)(benzo-κC)([c]benzo[4,5]imidazo-κN)[1,2-a][1,5]naphthyridine, Pd3O8-Py5, and the other with blue fluorescence emission. An optimized device structure achieves high color stability under various current densities, an external quantum efficiency (EQE) of 45.5%, a power efficiency of 97.4 Lm W-1 , and an estimated LT95 (operational time to 95% of the initial luminance) of 50 744 h at an initial luminance of 1000cd m-2 .

Tripyridylbenzene-based blue dendrimer emitters for efficient solution-processable single-emissive-layer hybrid white organic light-emitting diodes

A series of light-emitting dendrimers T42Bn, T24Bn, T26Bn and T35Bn based on electron-donating units of the second-generation butyicarbazoles (G2Cz) as dendrons and electron-withdrawing core of tripyridylbenzene (TPB) were designed and synthesized. The desirable blue luminogens were obtained due to the rational molecular design based on the twisted skeleton of all the molecules despite the donors of G2Cz moieties connected to the central acceptors of TPB via a para-phenylene bridge. Their thermal, photophysical, density functional theory calculation and electrochemical properties were fully investigated. Thanks to the excellent thermal stability, film-forming ability as well as the favourable energy levels of the dendrimers, efficient solution-processed hybrid white organic light-emitting diodes (WOLEDs) were achieved by employing these blue dendrimers and the orange emitter of (acetylacetonato)-bis[2-(thieno [3,2-c]pyridin-4-yl)phenyl]iridium(III) (PO-01) as an emitting layer (EML). Among them, the device based on T42Bn exhibited the highest maximum current efficiency (CEmax) of 10.25 cd/A with a maximum external quantum efficiency (EQEmax) of 3.94% and Commission International de I'Eclairage (CIE) coordinates of (0.34, 0.39), benefiting from the largest ƞPLQY and the highest electron transport capability of T42Bn and thus the enhancement of charge carrier balance in the device. In addition, the CIE coordinates of all the single-emitting-layer fluorescence/phosphorescence hybrid devices are very close to the benchmark white region of (0.33, 0.33). Our findings demonstrate the potential candidates of the solution-processable blue dendronized emitters for applications in full-color flat-panel displays and white lighting.

Improving excitons utilization of blue thermally activated delayed fluorescence emitter to achieve highly efficient solution-processed hybrid white organic light-emitting diodes

5-(5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)-10,15-diphenyl-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (DBA-DI) with high triplet energy was utilized as efficient blue emission dopant to construct solution-processed thermally activated delayed fluorescence-phosphorescence (TADF-phosphorescence) hybrid white organic light-emitting diodes (WOLEDs). Meanwhile, a series of TADF-phosphorescence hybrid WOLEDs composed of bis(2-phenylquinoline) (2,2,6,6-tetramethylheptane-3,5-dionate)iridium(III) (PQ2Ir(dpm)), tris(2-(4-tolyl)-phenylpyridine)iridium (Ir(mppy)3) and DBA-DI are successfully developed by introducing the co-host system consist of poly(N-vinylcarbazole) (PVK) and 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPy) with high color rendering index (CRI) and improving the utilization of triplet excitons. Furthermore, energy transfer processes among different emitters were investigated in detail based on absorbance spectra, photoluminescence and transient photoluminescence spectra. Ultimately, the Commission Internationale de I'Eclairage coordinates of the optimum solution-processed WOLEDs in warm-white emission region are (0.41, 0.41) and high CRI is 82. Furthermore, the same device realized outstanding efficiencies of 32.14 cd A−1, 21.00 lm W−1 and 15.1% at high brightness of 1000 cd m−2.

Robust sky-blue aggregation-induced delayed fluorescence materials for high-performance top-emitting OLEDs and single emissive layer white OLEDs

The development of blue luminescent materials plays a crucial role in the industry of organic light-emitting diodes (OLEDs). Herein, two sky-blue luminescent materials (mCP-BP-DMAC and DCB-BP-DMAC) comprised of electron donors of 9-(3-(9H-carbazol-9-yl)phenyl, 9-(4-(9H-carbazol-9-yl)phenyl and 9,9-dimethyl-9,10-dihydroacridine and electron acceptor of benzoyl are synthesized and characterized. They exhibit excellent thermal and electrochemical stabilities, strong aggregation-induced delayed fluorescence and bipolar carrier transport ability, and behavior efficiently in nondoped and doped bottom-emitting OLEDs with high external quantum efficiencies (ηexts) of up to 26.6% and small efficiency roll-offs. Efficient top-emitting OLEDs employing mCP-BP-DMAC and DCB-BP-DMAC as emitters are also achieved, providing sky-blue lights with high color purity and impressive ηexts over 30%. In addition, hybrid white OLEDs with stable emission color and high color rendering index are fabricated based on a single emissive layer consisting of orange-red phosphorescent Ir(MDQ)2acac dopant and sky-blue mCP-BP-DMAC and DCB-BP-DMAC hosts, furnishing excellent ηexts of up to 24.1% and small efficiency roll-offs. These results demonstrate mCP-BP-DMAC and DCB-BP-DMAC are outstanding luminescent and host materials with great application potentials in display and lighting devices.

Design and synthesis of D-A-D′ type compounds with AIE characteristics for hybrid WOLED with stable chromaticity

A series of donor–acceptor–donor’ (D-A-D′) type compounds with aggregation-induced emission (AIE) were designed and synthesized by using imidazole as an acceptor and triphenylamine and indolocarbazole as different donors. The non-coplanar structure could effectively eliminate the molecular aggregation-caused quenching (ACQ). Meanwhile, the electron push-pull character could be adjusted by introducing different substituents to achieve the high-efficiency fluorescence from its locally excited (LE) state. The electronic structures, electrochemical behavior, thermal stability, photophysical properties and electroluminescence (EL) performance of these compounds were systematically studied. Four new materials were evaluated as the blue emitters in non-doped OLEDs, and all devices present stable blue emissions with premium EL performance. Furthermore, a hybrid white organic light-emitting diode (WOLED) was prepared by using the compound 5b as the double blue emitting layer and the compound 5d as the host doping with phosphorescent dye. The maximum current efficiency and external quantum efficiency of the device were 67.6 cd/A and 24.3%, respectively. Especially, the WOLED showed ultra-stable CIE coordinates of (x = 0.337 ± 0.003, y = 0.341 ± 0.002) as the driving voltage increases from 5 V to 12 V. This work provides an idea for the design of AIE molecules and a practical strategy to achieve multifunctional light-emitting devices.

Efficient hybrid white organic light-emitting diodes with superior color stability and slow efficiency roll-off based on ultrathin emitting layer structures

In this work, high-performance hybrid white organic light-emitting diodes (WOLEDs) with high efficiencies, slow roll-off and excellent color stability were realized by strategically inserting ultrathin red phosphorescent emitter film into bluish-green thermally activated delayed fluorescent (TADF) light-emitting layer (EML). Experimental results demonstrated that the introduction of ultrathin phosphor film helps to harvest superfluous triplet excitons within bluish-green EML and relieve local exciton accumulation-induced quenching, thereby guaranteeing high exciton utilization probability. Besides, the strong holes' trapping of ultrathin layer leads to improved carriers balance, thus realizing stable recombination zone. Finally, the optimal hybrid WOLED obtained the maximum current efficiency (ηc), power efficiency (ηp) and external quantum efficiency (EQE) of 63.84 cd A−1, 66.06 lm W−1 and 28.16%, respectively. At the brightness of 1000 cd m−2, ηc, ηp and EQE as high as 57.14 cd A−1, 49.88 lm W−1 and 25.23%, respectively, can still be remained by the same device, manifesting slow efficiency roll-off. In addition, the resulting WOLED displayed excellent color stability with slightly shifted Commission Internationale de l’Eclairage coordinates (CIEx,y) from (0.43, 0.44) at 1000 cd m−2 to (0.41, 0.43) at 10000 cd m−2.

Creation of a thermally cross-linkable encapsulated TADF molecule for highly efficient solution-processed hybrid white OLEDs

Robust luminogens that can be used in application for high efficiency solution-processed hybrid white organic light-emitting diodes (WOLEDs) are rarely reported. Herein, a thermally cross-linkable encapsulated thermally activated delayed fluorescence (TADF) molecule, DVCz-2CzCN, consisting of blue emissive core, encapsulation unit and thermal cross-linkable group is designed and synthesized. Systematic studies demonstrate that DVCz-2CzCN as the emitter can form a stable and uniform thin film by the solution-process, and simultaneously suppress the triplet excitons concentration quenching. Consequently, the nondoped blue solution-processed device using DVCz-2CzCN as the emissive layer exhibits blue emission with maximum external quantum efficiency (EQE) of 5.6% is achieved. Especially to solution-processed hybrid WOLED with the construction of employing the cross-linked DVCz-2CzCN as the blue-emitting component combined with an orange-emitting phosphor PO-01, exhibits a superior performance with maximum forward-viewing EQE of 14.9% and a stable Commission International de L'Eclairage (CIE) coordinate of (0.33, 0.45). This work indicates that molecular topology construction is crucial for the development of high-performance solution-processed hybrid WOLEDs. Herein, a highly efficient solution-processed hybrid white OLED was reported based on the strategy of constructing a thermally cross-linkable encapsulated TADF molecule. • Solution-processed hybrid white OLED was fabricated by utilizing a thermally cross-linkable encapsulated TADF molecule. • DVCz-2CzCN possesses good morphologic stability, sufficient solvent resistance and efficient triplet excitons confinement. • The DVCz-2CzCN-based device can afford a high blue TADF OLED by the solution-process with EQE max of 5.6%. • Solution-processed hybrid white OLED exhibits a superior performance with EQE max of 14.9%.

Efficient exciton regulation for high-performance hybrid white organic light-emitting diodes with superior efficiency/CRI/color stability based on blue aggregation-induced emission fluorophor

Fluorescent/phosphorescent hybrid white organic light-emitting diodes (WOLEDs) combining blue aggregation-induced emission (AIE) fluorophors with efficient yellow (or green/red) phosphors have attracted more attention in applications of full-color display and solid-state lighting. However, it is still a major challenge for hybrid WOLEDs based on AIE-active fluorophors to simultaneously realize high efficiency, high color rendering index (CRI), good color stability and low efficiency roll-off. Here, a sky-blue AIE fluorophor as the neat emitter has been successfully applied to high-performance blue OLED and two-/three-color hybrid WOLEDs. The blue device with a high exciton utilization efficiency of 47.4%–71.1% realizes the external quantum efficiencies (EQEs) of 6.3 and 5.5% at 1000 and 5000 cd m −2 . By accurately managing the arrangement of emissive layers, Three-color WOLED without the damage of deep-blue light not only realizes high efficiencies of 41.6 cd A −1 and 46.6 lm W −1 , but also shows a high CRI over 80 and good color stability with the Commission Internationale de L'Eclairage (CIE) coordinates changing from (0.432, 0.480) to (0.418, 0.488) when the driving voltage increases from 4 to 7 V, meeting the requirement for energy-saving and healthy lighting source. Such excellent EL performance is really rare in the no deep-blue light damage, high CRI and good color stability hybrid WOLEDs based on AIE-active fluorophor. High efficiency hybrid WOLEDs with no deep-blue light damage, good color stability, and high CRI over 80 have been achieved based on blue aggregation-induced emission fluorophor. • A blue AIE-active fluorophor realizes theEQEs of 6.3 and 5.5% at 1000 and 5000 cd m −2 . • The WOLED with no deep-blue light damage, high CRI over 80, and color stability is realized. • The WOLED shows the -forward-viewing current efficiency of 41.6 cd A −1 , and remains as high as 38.7 and 36.8 cd A −1 at 100 and 1000 cd m −2 .

Systematic strategy for high-performance small molecular hybrid white OLED via blade coating at ambient condition

Large-area organic light-emitting diodes (OLEDs) fabricated by solution process with low-cost are essential for practical applications. However, maintaining desirable uniformity and smoothness of prepared films are challenging with the enhancement of film size and layers. Reported herein is a systematic strategy of solvent and device structure engineering for designing small molecular hybrid white OLED (WOLED) via blade-coating. Benefiting from the uniform blade-coated films with low roughness about 1 nm as well as the balanced charge carrier transport, the blade-coated WOLED with hybrid fluorescence and phosphorescence (small area 0.1 cm 2 ) shows the maximum current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) of 29.0 cd A −1 , 30.4 lm W −1 , and 11.6%, respectively. And the WOLEDs achieve low turn-on voltage ( V on ) of about 2.8 V. Meanwhile, the all-vacuum-based WOLED reaches maximum CE, PE, and EQE of 40 cd A −1 , 44.3 lm W −1 , and 15.9%, respectively. Remarkably, a larger area of the device (2 cm × 2 cm) with uniform emitting reaches peak EQE of 6.8% by blade-coating, notably, only a small amount of solution about 0.9 μL/cm 2 was consumed for blade-coated films. The high-performance and low-cost WOLED via blade-coating is ascribed to the facile strategy to improve the film morphology and the energy-level matching, which provides huge potential in display and flat panel lighting. Benefiting from the solvent and device structure engineering, the blade-coated hybrid white organic light-emitting diodes (WOLEDs) reach external quantum efficiencies (EQEs) close to 12% (small-area, 0.1 cm 2 ) and 6.8% (2 cm × 2 cm) with a small amount of solution about 0.9 μL/cm 2 . • Fabricating a hybrid white organic light-emitting diodes (WOLEDs) by blade-coating at ambient conditions. • Selecting the ideal solvents (solvent engineering) and electron-transporting layer for the highly efficient blade-coating WOLED which reaches the maximum EQE, power efficiency (PE), and current efficiency (CE) of 11.6%, 30.4 lm W −1 , and 29.0 cd A −1 , respectively. • Fabricating a blade-coated WOLED (2 cm × 2 cm) owning peak EQE of 6.8% with a small amount of solution of 0.9 μL/cm 2 .

A linear deep-blue bipolar fluorescent material with the CIEy < 0.065 serving as the emitter and host for high-performance monochromatic and hybrid white OLEDs

A linear deep-blue HLCT material P2MPC served as the emitter and host in high-performance monochromatic and hybrid white OLEDs.

A Promising Multifunctional Deep‐Blue Fluorophor for High‐Performance Monochromatic and Hybrid White OLEDs with Superior Efficiency/Color Stability and Low Efficiency Roll‐Off

AbstractHigh‐performance deep‐blue fluorescent materials matching the required Commission Internationale de l'Eclairage y coordinate value (CIEy) of < 0.08 are much‐needed in organic light‐emitting diodes (OLEDs) for realizing the perfect application of full‐color displays. However, deep‐blue fluorophors commonly show unsatisfactory performance due to the intrinsic large bandgap characteristic. Here, the deep‐blue nondoped OLED with the good CIE coordinates of (0.15, 0.07) and external quantum efficiency (EQE) of ≈9% is achieved based on a multifunctional and efficient anthracene‐based fluorophor (2M‐ph‐3CzAnBzt). Using it as a host, the sky‐blue fluorescent OLED realizes the maximum EQE of 9.50%, and keeps as high as 9.27% and 8.56% at 1000 and 5000 cd m−2. More surprisingly, high‐performance hybrid white OLEDs (WOLEDs) with good color stability and low roll‐off are achieved by using it as the blue emitter. Two‐color WOLED shows the forward‐viewing efficiencies of 20.46%, and 76.80 lm W−1. The three‐color WOLED emitting a candlelight with the color rendering index of ≥ 82 realizes the maximum EQE of 21.49% and remains 20.80% at 1000 cd m−2. Such superior electroluminescence performance achieved in these OLEDs ranks among the highest values based on deep‐blue fluorophors with CIEy < 0.08.

Highly Efficient and Solution‐Processed Single‐Emissive‐Layer Hybrid White Organic Light‐Emitting Diodes with Tris(triazolo)triazine‐Based Blue Thermally Activated Delayed Fluorescence Emitter

AbstractSolution processable organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) emitters show inferior efficiency to devices produced via vacuum deposition. In this context, solution‐processed hybrid white OLEDs are fabricated using a TADF molecule and iridium complex as the blue and red dopants, respectively. First, solution‐processed OLEDs employing a tristriazolotriazine‐based TADF as the blue dopant are designed and fabricated, yielding maximum external quantum efficiency (EQEmax) of 23.23% with an emission peak at 492 nm. Use of the optimized tristriazolotriazine‐based TADF OLED structure and additional red phosphor achieves highly efficient white light emission with an EQEmax of 22.57%, stable Commission International de l'Eclairage (CIE) coordinates of (0.34, 0.34), a correlated color temperature of 5000 K, and a color rendering index of 73. Impressively, accelerated lifetime testing shows the white OLED possessing a lifetime to 80% of initial luminance (LT80) of 40 h, and an LT50 of 298 h. To the best of knowledge, the device performance demonstrated in this work is one of the best comprised of solution‐processed blue and fluorescent‐phosphorescent hybrid white OLEDs. This research provides a reliable method for high efficiency solution processable blue TADF and TADF‐phosphorescent hybrid OLEDs.

High‐Performance Hybrid White OLEDs with Ultra‐Stable Emission Color and Small Efficiency Roll‐Off Achieved by Incorporating a Deep‐Blue Fluorescent Neat Film

AbstractOrganic blue luminescent materials play a vital role in the fabrication of full‐color displays and white lighting devices, but high‐efficiency blue emitters that meet commercial demands are still quite insufficient. Herein, the authors wish to report the design and synthesis of four bipolar deep‐blue luminogens consisting of an anthracene core and various functional groups. Their photophysical properties, electronic structures, electrochemical behavior, thermal stability, carrier transport ability, and electroluminescence performance are systematically studied. The nondoped organic light‐emitting diode (OLED) based on DPAC‐TAn‐BI radiates stable deep‐blue light [Commission Internationale de l'Eclairage (CIEx,y) = 0.15, 0.15] with a high external quantum efficiency (ηext) of 5.81%. Moreover, efficient two‐color hybrid warm white OLEDs are achieved using DPAC‐TAn‐BI neat film as a blue‐emitting layer, providing an excellent ηext of 27.6%, a small efficiency roll‐off of 2.9% at 1000 cd m−2, and ultra‐stable emission spectra with tiny CIEx,y variation of (0.01, 0.01) from 100 to 10 000 cd m−2. These results demonstrate that the deep‐blue luminogens are strong candidates for applications in blue and white OLEDs.